Comminuting devices which use a high speed rotating turbine to reduce the size of and to separate particulate materials have been in existence for quite some time. Devices of this type are found in the patents attributed to Rolle, et al. (U.S. Pat. Nos. 4,852,818; 4,718,609; and 4,892,261). The turbine component of the device is made of a plurality of air foil blades mounted on a backing plate and is dimensioned in close tolerances to a housing. Mounted in front of the turbine blade and its housing is an expansion chamber of frusto-conical shape.
In these devices, material to be comminuted is carried in an air stream through an acceleration tube and into the expansion chamber, where it is rapidly decompressed, causing it to explode. The spinning turbine produces a negative pressure in the expansion chamber and introducing raw materials at a specific rate into the chamber allows air trapped in the material to expand in the negative pressure environment, thereby causing the explosion of the material into smaller particles. The smaller particles can then be size-separated by methods well known in the art, such as by a specific gravity separator.
It is known in the art of comminuting devices that adjusting the negative pressure achieved by the device results in variations in particle size dimensions. Known methods for varying the negative pressure include varying the RPM of the turbine and varying the length of the expansion chamber. However, the art has not addressed varying the design of the turbine blades or the leading edges of the turbine blades to help achieve further fine tuning of the negative pressure variants achievable in comminuting devices.
The foregoing reflects the state of the art of which the inventor is aware, and is tendered with a view toward discharging the inventor's acknowledged duty of candor, which may be pertinent to the patentability of the present invention. It is respectfully stipulated, however, that the foregoing discussion does not teach or render obvious, singly or when considered in combination, the inventor's claimed invention.